by Thomas J. Coates and Chris Collins

About the authors: Thomas J. Coates is the director of the AIDS Research Institute at the University of California, San Francisco. Chris Collins is an appropriations associate for Congresswoman Nancy Pelosi of San Francisco.

With a vaccine still years away, the only broadly applicable way to prevent new HIV infections is to change behaviors that enable transmission of those infections—especially behaviors relating to sex and drug injection.

Because most people simply will not choose celibacy, realistic public health workers have focused on encouraging adoption of safer sexual practices, notably condom use. That people can be persuaded to employ safer sex is well illustrated by the experience of San Francisco’s gay community in the 1980s. Perhaps 8,000 individuals became infected with HIV in both 1982 and 1983. That figure declined to 1,000 a...